Expanding Snow Lab Pack
M13L
Contents
Snow polymer powder
Plastic cups (100 mL)
Measuring spoon (5 mL)
105 g
30
5
You will also need
One or two large containers with luke warm water
24 plastic plates
Ziplock bags so students can take the snow home
Students prepare fluffy, dry white snow from a polymer and water.
PROCEDURE (for 24 students)
1. Add the snow powder to easily accessible containers and have each student measure 1.5 teaspoons
(7.5 mL) snow polymer to a 100 mL plastic cup using the measuring spoon. As accurately as possible!
(Show them how to measure one level and one half teaspoon).
2. Place the 24 cups on paper sheets, disposable plates or plastic trays.
3. Each student now adds a full cup of water (100 mL) as quickly as possible to the snow powder.
It should be done in one second!! (We have provided 6 cups for this action).
4. See a snowstorm erupting! The 7.5 mL should expand in volume to 300 mL snow!
A note on the water: The absorption process is an osmotic one, so the best absorption will be with luke
warm water that is as clean as possible from dissolved salts. First try the reaction with tap water - it should
work OK. If not, get distilled water.
FURTHER INVESTIGATION
• Freeze the snow in a ziplock bag. Did it shrink or expand?
• What happens when more water is added?
• Make coloured snow by adding 3 drops of food colouring to the 100 ml
water.
• Sprinkle table salt on the snow. The snow releases the water after a few
seconds through a process
of reverse osmosis.
• Experiment with different water qualities. Vary the pH and the salt
content and record the volume yield each time.
WHAT IS HAPPENING?
Instant snow is a sodium salt of a crosslinked polyacrylic acid. It is used as artificial snow on ski slopes and
film sets. It easily expands to 40 times its original volume and can soak up water to more than 100 times its
own mass. Industrially it is used for spill containment and as blood absorber in hospitals. The crosslinked
molecules have a high sodium content and absorb water through a process known as osmosis and expand
as the water moves in. In this process water passes through a membrane to an area with higher salt and
lower water concentration. (Place raisins in water to demonstrate osmosis to students (leave for 24 hours)).
DISPOSAL
Do not dispose of the snow. Once the water evaporates, the snow powder shrinks back and can be recycled
with water although never as spectacular as the first time. If you want, you can dispose of the snow in the
garden or garbage bin. It makes a great moist absorber for plants as it is non-toxic and bio-degradable.
SAFETY
• Sodium polyacrylate is classified non-hazardous, but the dry polymer may be irritating to the eyes and
skin. If necessary wash affected area under running water. Obtain medical attention if the irritation
persists. Ingestion of the dry polymer may be harmful. If ingested, induce vomiting. Seek medical
attention.
• The snow polymer is slippery when wet. Keep off walking surfaces and clean all spills immediately.
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